The invention relates to an air spring system of a motor vehicle with the system having a tire-fill connection for filling the tire of a spare wheel.
U.S. patent application Ser. No. 10/240,823, filed Oct. 7, 2002, discloses configuring the spare wheel of a motor vehicle as a folding wheel which is filled only when needed.
The compressor of the level control system can be used for pumping up the folding wheel in a vehicle equipped with air springs. For this purpose, the motor vehicle air spring system is equipped with tire-fill components.
The structure of the self-diagnosis in conventional level control systems having a tire-fill connection provides that, as a direct reaction to a detected fault, all system components which are directly affected by this fault transfer into a safe state. For example, for an electrical fault at the compressor relay, the compressor is transferred into the reliable state xe2x80x9coffxe2x80x9d.
For the tire-fill connection, this means that a tire filling is no longer permissible when there is an electrical fault at the contacts, that is, the tire-fill connection can no longer be used.
The above means that, when the diagnosis xe2x80x9ctire-fill connection faultxe2x80x9d is made, a tire filling was not permitted up to now for such air spring systems which are supplemented to include tire-fill components. Accordingly, it can happen for an electrical fault (for example, because of a short circuit or a line interruption), that neither a refilling takes place nor is a warning outputted to the driver. The present invention overcomes this unwanted situation.
The method for filling a spare wheel according to the invention is primarily applicable in vehicle systems having an air spring level control system and tire-fill hardware.
The method of the invention is for filling a tire of a spare wheel utilizing an air supply unit of an air spring system of a motor vehicle equipped with a tire filling system including a tire-fill connection unit and a fill unit. The arrangement includes: in a fault-free condition, changing the logic states of the inputs (32a, 32b) of a reed switch connected to a control apparatus from low/high to high/low when the tire-fill connection unit is attached; in a fault-free condition, changing the logic states of the inputs (32a, 32b) from high/low to low/high when disconnecting the tire-fill connection unit; the control apparatus functioning to detect high/high and, when the high/high is detected, then concluding either the third input (32c) has undergone a short circuit to positive or the second input (32b) has undergone a line interruption (or short circuit to positive) which cannot be diagnosed when the tire-fill connection unit is not attached; and, the control apparatus functioning to detect low/low that, when the low/low is detected, then concluding that either the second input (32b) or the third input (32c) has a short circuit to ground which can be diagnosed when said tire-fill connecting unit is not mechanically attached and the fill operation can be started when only one of the first and second inputs (32a, 32b) changes its logic state.
The method of the invention permits filling a spare wheel of a motor vehicle even when there is an electrical fault in the level control system of the air spring system.
With the method and arrangement of the invention, a significantly higher availability of the special function xe2x80x9creserve wheel fillingxe2x80x9d is provided. This is explained with the aid of two examples below.
A vehicle travels off road and the driver selects the largest possible ground clearance via the level operator-controlled component. An electrical fault is diagnosed (for example, a short circuit to the positive terminal) without the driver having connected the tire-fill connection. The consequence here is that the control level system operates in a special emergency condition designed for this situation, that is, manual control operations are no longer permitted in order to avoid travel-dynamic critical situations. Only speed control takes place. The tire-fill function now operates pressure orientated, that is, a pressure of 4.5 bar is built up up to the outlet valve. If now the tire-fill connection unit is connected, the tire is filled. If the driver actuates the operator-manipulated component, then the reserve wheel is filled.
The same start conditions are present as in Example 1. Here, the driver wants to eliminate a flat tire. In this instance, when the driver attaches the tire-fill tube, a sleeping fault is detected (for example, a short circuit to ground is first detected because, with the attachment, only the closing contact changes its state). The consequence here is that the level control system operates in a special emergency mode for this situation, that is, all manual control operations are no longer permitted in order to prevent travel-dynamic critical situations. Only speed conditioned controls take place. The tire-fill function operates pressure orientated, that is, a pressure of 4.5 bar is built up up to the outlet valve. If the tire-fill tube is now attached, then this too will be filled. If the driver actuates the manual operator-controlled unit, then the spare wheel is filled.